--- a/scripts/general/isa.m
+++ b/scripts/general/isa.m
@@ -30,15 +30,41 @@
     print_usage ();
   endif
 
+  persistent float_classes = {"double", "single"};
+
+  persistent fnum_classes = {"double", "single", ...
+			     "uint8", "uint16", "uint32", "uint64", ...
+			     "int8", "int16", "int32", "int64"};
+
   if (strcmp (cname, "float"))
-    retval = (strcmp (class (x), "double") || strcmp (class (x), "single"));
+    retval = any (strcmp (class (x), float_classes));
   elseif (strcmp (cname, "fnumeric"))
-    retval = (strcmp (class (x), "double") || strcmp (class (x), "single") ||
-    strcmp (class (x), "uint8") || strcmp (class (x), "uint16") ||
-    strcmp (class (x), "uint32") || strcmp (class (x), "uint64") ||
-    strcmp (class (x), "int8") || strcmp (class (x), "int16") ||
-    strcmp (class (x), "int32") || strcmp (class (x), "int64"));
+    retval = any (strcmp (class (x), fnum_classes));
   else
     retval = strcmp (class (x), cname);
   endif
+
 endfunction
+
+%!assert (isa ("char", "float"), 0)
+%!assert (isa (double (13), "float"), 1)
+%!assert (isa (single (13), "float"), 1)
+%!assert (isa (int8 (13), "float"), 0)
+%!assert (isa (int16 (13), "float"), 0)
+%!assert (isa (int32 (13), "float"), 0)
+%!assert (isa (int64 (13), "float"), 0)
+%!assert (isa (uint8 (13), "float"), 0)
+%!assert (isa (uint16 (13), "float"), 0)
+%!assert (isa (uint32 (13), "float"), 0)
+%!assert (isa (uint64 (13), "float"), 0)
+%!assert (isa ("char", "fnumeric"), 0)
+%!assert (isa (double (13), "fnumeric"), 1)
+%!assert (isa (single (13), "fnumeric"), 1)
+%!assert (isa (int8 (13), "fnumeric"), 1)
+%!assert (isa (int16 (13), "fnumeric"), 1)
+%!assert (isa (int32 (13), "fnumeric"), 1)
+%!assert (isa (int64 (13), "fnumeric"), 1)
+%!assert (isa (uint8 (13), "fnumeric"), 1)
+%!assert (isa (uint16 (13), "fnumeric"), 1)
+%!assert (isa (uint32 (13), "fnumeric"), 1)
+%!assert (isa (uint64 (13), "fnumeric"), 1)